Hydrodynamic unit with mechanical drive clutch

ABSTRACT

This hydrodynamic unit has a friction clutch that is selectively engageable to establish a mechanical power path through the unit to improve power transmission efficiency under predetermined operating conditions. A clutch control chamber is automatically hydraulically connected to the torus chamber of the unit by special valve means to reduce clutch capacity to a point where the clutch does not transmit appreciable torque in response to the transition from an engine drive condition to an overrun condition. With clutch capacity so reduced the backlash in the drive unit is effectively dissipated by the fluid in the unit and is not transmitted mechanically to the engine.

United States Patent [191 Annis et al.

HYDRODYNAMIC UNIT WITH MECHANICAL DRIVE CLUTCH Inventors: Robert E.Annis, Howell; Forrest R.

Cheek, Detroit, both of Mich.

General Motors Detroit, Mich.

Filed: Nov. 18,1971

Appl. No.: 200,007

Assignee: Corporation,

US. Cl ..192/3.3, 192/41 R, 192/56 F, 192/86 Int. Cl ..F16d 39/00 Fieldof Search ..192/56 F, 3.29, 3.3, l92/3.33

References Cited UNITED STATES PATENTS 3/1966 Crosswhite et al...l92/3.33 X 5/1966 Maurice ..192/3.3 5/1964 Brise ..192/3.33 X

3,228,503 1/1966 Maurice l92/3.33 X 3,410,378 11/1968 Maurice ..192/3.333,415,345 12/1968 Cadiou ..192/3.33

Primary Examiner-Benjamin W. Wyche Attorney-W. E. Finken et al.

[57] ABSTRACT This hydrodynamic unit has a friction clutch that isselectively engageable to establish a mechanical power path through theunit to improve power transmission efficiency under predeterminedoperating conditions. A clutch control chamber is automaticallyhydraulically connected to the torus chamber of the unit by specialvalve means to reduce clutch capacity to a point where the clutch doesnot transmit appreciable torque in response to the transition from anengine drive condition to an overrun condition. With clutch capacity soreduced the backlash in the drive unit is effectively dissipated by thefluid in the unit and is not transmitted mechanically to the engine.

5 Claims, 3 Drawing Figures HYDRODYNAMIC UNIT WITH MECHANICAL DRIVECLUTCH This invention relates to a hydrodynamic unit having aselectively engageable clutch for establishing a mechanical power pathfrom an input to an output through the unit and which automaticallydisengages in response to a reversal in power flow into the unit such asthe power flow from the output to the input.

Selectively engageable friction drive clutches have been employed inconverter and coupling units of vehicle transmissions to provide amechanical drive connection between the input and output of the unitunder predetermined operating conditions to reduce unit slip losses andthereby improve transmission operating efficiency. When cruising forexample, this friction drive clutch is engaged to remove the slipbetween the input and output rotor members by mechanically connectingthem together. The application and popularity of hydrodynamic units withfriction clutches is increasing particularly where increased economy ofoperation is of prime importance. However, these units when locked ordrivingly connected by the friction clutch do not provide for the fluidcushioning and absorption of any shocks or rough operation such as mightoccur when there is a transition from an engine drive condition to anoverrun condition. When this occurs with such a clutch engaged thebacklash in the entire drive line is reversed and the resultingmechanical jar or clunk is transmitted through the clutch to the engine.This invention utilizes the reversal of load direction for automaticallyreleasing the clutch, thus uncoupling the mechanical connection from theturbine to the engine so that the hydraulic fluid in the unit canfunction as a fluid damper to reduce the jar of the backlash.

In the preferred embodiment of this invention a clutch is provided in ahydraulic coupling or converter which has a disk-like pressure platewith an outer friction disk that cooperates with the front cover of theunit to form a clutch control chamber within the torus chamber of thehydrodynamic unit. The pressure plate has a drive pin press fittedtherein which extends into an opening formed within the turbine hub.This latter opening is larger in diameter than the pin and ishydraulically connected with the torus chamber. The pin has a fluidpassage therein which leads from the clutch chamber into the opening inthe turbine hub and cooperates with the opening to form control valvemeans for the clutch control chamber. When the impeller speed is greaterthan the speed of the turbine, the pin is moved relative to the turbinehub to a position in which the wall forming the opening closes thepassage in the pin to seal the clutch chamber from the torus chamber.Under these conditions the clutch can be selectively engaged anddisengaged by the controlled pressure fed into the clutch chamber. Whenimpeller speed is less than that of the turbine the pressure plate anddrive pin are relatively moved to a position so that the passage isopened and the pressure in the clutch chamber is bydraulically connectedwith the torus chamberto cause the reduction in capacity of the clutch.This occurs when there is overrun of the impeller by the turbine so thatbacklash occurring in the drive line will be dissipated by the fluidunit and will not be transmitted mechanically by the clutch which is, ineffect, disengaged. It is a feature and object of this invention toprovide a new and improved friction clutch in a fluid unit which whenpower flows in a first direction to the unit is selectively engageableto establish a mechanical drive through the unit to improve operatingefficiency under predetermined operating conditions and whichautomatically disengages in response to a reversal of power flow to theunit so that torque is transmitted only by the fluid unit.

Another feature and object of this invention is to provide a new andimproved means for automatically releasing a torque converter or fluidcoupling clutch when the vehicle goes from a drive to a coast or overrunmode of operation. The reversal of load direction releases the clutch toeliminate the mechanical connection from the turbine to the engine toallow the hydraulic fluid in the converter to function as a fluiddampener.

Another feature and object of this invention is to provide a new andimproved valve means within a fluid coupling or torque converter fordisengaging the clutch when there is a reversal ofdrive such as from thedrive line to the engine; the fluid in the unit absorbs the shock loadas the capacity of the clutch is decreased to a low capacity toeliminate the mechanical transmission of shocks to the input rotor ofthe unit.

These and other features and objects of the invention will become moreapparent from the following detailed description and from the drawing inwhich:

FIG. 1 is a cross-sectional view of an upper portion of a torqueconverter;

FIG. 2 is a view partly in section taken generally along the lines 2-2of FIG. 1;

FIG. 3 is a view of a detail of FIG. 2 showing the valve construction ofthis invention.

Referring now to FIG. 1, there is shown a hydrodynamic device 10 fordriving a gear unit such as shown in U.S. Pat. No. 3,321,056 to Winchellet al. which is operable to provide a plurality of forward drives and areverse drive. The hydrodynamic device 10 is of the torque convertertype and comprise a front cover 12 which is connected by lugs 14 to theengine of a vehicle and which is welded to a rear cover 16 to provide arotary converter housing that encloses an annular converter chamber ortorus 18. A series of vanes 20 is secured to the rear cover 16 and to aradially spaced inner shell 22 to provide an impeller I that rotateswith the engine. A second series of vanes 24 secured to outer and innerannular shells 26 and 28 to form a turbine T which is drivinglyconnected to an annular hub member 30 by connector pins 34 that extendthrough an inner flange portion of shell 26 and through the hub member.The hub member is splined at 36 to a turbine output shaft 38 whichserves as the input to the gear unit. A series of blades 40 which areintegral with a hub 44 are disposed between the inner ends of theturbine and impeller blades provides a stator S. The stator is permittedfree rotation in the same direction as the impeller by a one-way brake48 which is disposed between an outer race 50 and an inner race 52. Theinner race is splined to a sleeve 54 which is grounded at its rear endto a front bulkhead 56 that is secured by bolts 58 to the stationaryhousing 59 of the transmission and is located between the torqueconverter 10 and the gear unit.

The torque converter structure thus far described is conventional and onsupply of fluid to the chamber 18 at a suitable charge pressure operatesto provide torque multiplication between the impeller l and turbine T todrive the converter output shaft 38 and thus the gear unit. From astationary vehicle position to a cruising condition the torquemultiplication provided by hydrodynamic converter progressivelydecreases as turbine speed progressively increases and approaches thatof the impeller at which time the torque converter then acts as a fluidcoupling to continue the drive of the output shaft 38; the one-way brake34 permitting the stator to free-wheel in the forward direction duringcoupling operation.

The rear cover 16 is welded at its rear face to a sleeve 60 that isconnected at its rear end by a tongue and slot connection 62 to drive anexternal toothed gear 65 of a conventional internal-external gear typepump 66. The pumps internal tooth gear 68 together with the externaltooth gear 65 are mounted in a pump housing 70 which is bolted to thefront side of bulkhead 56.

According to the present invention there is provided in the torqueconverter a fluid pressure operated clutch 72 that is selectivelyengageable to provide a mechanical drive between the rotary converterfront cover 12 and the converter output shaft 38. This mechanical driveis thus in parallel with the normal hydraulic drive to drive the gearunit. Clutch 72 has an annular plate 74 with a friction facing 76engageable with an annular radially extending face 78 formed on the rearside of the front cover 12 within the rotary converter housing. Thefriction plate 76 is drivingly connected to an annular disc or pressureplate 80 which has a central opening 82 through which the forward end ofthe converter output shaft 38 extends. There is no drive connectionbetween opening 82 and shaft 38 so there can be limited relative turningmovement between disc 80 and the shaft 38 as will be explained below.Disposed radially outwardly from the central opening 82 in disc 80 is asecond opening 84 in which there is rigidly secured a cylindrical drivepin 86 which projects inwardly from disc 80 into an axial cylindricalopening 88 formed in hub member 30.

As shown best by FIGS. 2 and 3 the opening 88 is slightly larger indiameter than the outer diameter of pin 86 to provide clearance 90therebetween. When the power flow is from the engine through the clutch72 to shaft 38 the clearance appears to the left side of the pin as inFIG. 2. On engine overrun when the power flow to the converter is fromthe shaft 38, the clearance 90 appears on the right side of the pin asshown in FIG. 3. Since there is clearance at 91 between turbine hub 30and disc 80 the clearance 90 is hydraulically connected at all positionsof pin 86 with the torus chamber 18.

As shown the pin is formed with an internal axial passage 92 which opensinto the chamber 94 formed between the disc 80 of the clutch 72 and thefront cover 12. Further pin 86 has a lateral passage 96 leading frompassage 92 which extends through the cylindrical wall thereof. Thislateral passage 96 communicates with clearance 90 when pin 86 is in theFIG. 3 position. Thus in FIG. 3 position the passage 92 and 96 providefor the hydraulic communication between annular converter chamber 18with clutch chamber 94. When pin 86 is in the FIG. 2 position thelateral passage 96 is blocked by' the wall of the hub member formingopening 88 so that chamber 18 and chamber 94 are sealed with respect toeach other.

Transmission controls 100 are provided for automatically controlling theoperation of the gear unit and the clutch 72. As shown clutch chamber 94is hydraulically connected to the controls through longitudinal passage102 having a flow control restriction 104 therein and through line 106which connects passage 102 with the controls. The pump 66 supplies thecontrols with pressure oil through line 108 that connects the pumpdischarge port 110 with the controls. Regulated pressure from thecontrols is fed into the converter inlet 112 through line 114 andconnecting passage 116. The converter discharges oil through port topassage 122 formed between the shaft 54 and the turbine shaft 38 andthrough passage 124 back to a sump in the controls 100 via a cooler.

Assuming that the converter is a torque multiplying phase of operation,the impeller speed will be greater than the turbine speed. Low pressureoil from the controls 100 is fed into chamber 94 so that the clutch 72has no appreciable load carrying capacity. However, plate 80 is turnedby the front cover to move pin 86 to the FIG. 2 position in which thelateral passage 96 is blocked by the wall of the turbine hub. Withlateral passage 96 effectively blocked, the chamber 94 is sealed from heconverter chamber 18. In the event that mechanical drive through theclutch 72 and drive pin 86 is desired for an all mechanical drive, theback pressure in chamber 94 is reduced so that the capacity of theclutch is accordingly increased. With the force of the transmissionfluid in chamber 18 effecting the full drive engagement of clutch 72,the impeller and turbine are drivingly connected together for thisdrive.

In a transition from an engine drive condition to an overrun conditionthe turbine T and its hub 30 overruns the pump I and the pin 86connected thereto through the clutch 72 to cause the hub 30 to moverelative to the pin 86 to the position shown in FIG. 3. Under theseconditions the lateral passage 96 is opened and chamber 94 is thus incommunication with the converter chamber 18. This reduces the pressuredifferential between chamber 94 and converter chamber 18; the torquetransmitting capacity of clutch 72 is thus reduced to a point where itdoes not transmit appreciable torque. With clutch 72 thus effectivelydisengaged the reversal of backlash in the drive line is absorbed inconverter slip and is not transmitted mechanically to the engine. Thusthis invention utilizes the reversal of load direction for releasing theclutch to eliminate the mechanical connection from the turbine to theengine to allow the hydraulic fluid within the converter to function asa fluid dampener.

Although only one drive pin 86 and cooperating opening 88 has been shownand described others can be added as needed to strengthen the driveconnection between the plate 80 and the turbine hub when clutch 72 is intorque transmitting engagement. One or any number of the pins can havethe passage 92 and 96 to provide for the automatic clutch valve of thisinvention.

The above-described preferred embodiment is illustrative of theinvention which may be modified within the scope of the followingclaims.

We claim:

'1. A power transmitting hydrodynamic unit comprising a housing defininga fluid chamber, input rotor means operatively connected to said housingfor circulating transmission oil in said unit, output rotor means forreceiving oil circulated by said input rotor means and for directingsaid oil back toward said input rotor means, torque transmitting meansoperatively connected to said output rotor means for transmitting thetorque developed thereon by the circulating oil within said unit, clutchmeans in said unit selectively engageable to operatively connect saidinput rotor means with said torque transmitting means, said clutch meansforming a clutch control chamber in said unit, drive means operativelyconnecting said clutch means to said output rotor means, and valve meansoperatively connected between said clutch means and said output rotormeans to establish hydraulic communication between said fluid chamberand said clutch chamber in response to the overrun of said input rotormeans by said output rotor means to reduce the load carrying capacity ofsaid clutch and also to seal said chambers from hydraulic communicationin response to the overrun of said output rotor means by said inputrotor means so that the load carrying capacity of said clutch can beincreased.

2. In a hydrodynamic unit comprising a rotatable drive plate and ahousing secured thereto to form a torus chamber, input rotor meansoperatively connected to said housing for rotation therewith to drivetransmission oil supplied to said chamber, output rotor means forreceiving oil circulated by said input rotor means and for directingcirculated oil back toward said input rotor means, selectivelyengageable clutch means operatively disposed in said torus chamber formechanically connecting and for disconnecting said input rotor means andsaid output rotor means, said clutch means having a clutch platedisposed adjacent to said drive plate to form a clutch control chamber,said output rotor means having a hub portion with an enlargedcylindrical opening therein, a drive means supported by said clutchplate which extends into said opening to form a fluid passage therewith,and fluid passage means in said drive means having an openingcooperating with said hub to hydraulically seal said clutch chamber fromsaid torus chamber when said input rotor means rotates faster than saidoutput rotor means so that the oil pressure in said torus chamber canurge said clutch into engagement and further cooperating with said hubto open said clutch chamber to the torus chamber when said output rotormeans rotates faster than said input rotor means to provide for thehydraulic communication of said chambers to cause the drivedisengagement of said clutch means and the disconnection of themechanical drive between said input and output rotor means.

3. A power transmitting hydrodynamic unit comprising a rotatable housingdefining a fluid chamber for receiving transmission oil, bladed inputrotor means operatively connected to said housing for circulatingtransmission oil within said unit, bladed output rotor means forreceiving oil circulated by said input rotor means and for dischargingtransmission oil in a circuitous path back toward said input rotormeans, torque transmitting means for transmitting torque developed bysaid output rotor means from the oil circulated thereto by said inputrotor means, connector means for drivingly securing said output rotormeans to said torque transmitting means, clutch means for mechanicallyconnecting and for disconnecting said input rotor means and said outputrotor means, said clutch means comprising clutch plate means operativelydisposed within said housing and cooperating directly therewith todefine a clutch control chamber separate from said fluid chamber, valvemeans operatively disposed between said plate means and said outputrotor means and responsive to the back drive of said output rotor meansby said torque transmitting means to hydraulically connect said clutchcontrol chamber and said fluid chamber so that said clutch meansdisconnects said input rotor means and output rotor means and beingfurther responsive to the drive of said torque transmitting means bysaid output rotor means to hydraulically block communication betweensaid clutch control chamber and said fluid chamber so that said clutchmeans can be engaged to drivingly connect said input rotor means andsaid output rotor means.

4. The power transmitting unit of claim 3, said unit having a bladedstator therein operatively disposed between said input and output rotormeans, a one-way brake for holding said stator from rotating in a firstdirection and permitting the rotation thereof in an opposite direction,said output rotor means having a hub fastened by said connector means tosaid torque transmitting means, said valve means comprising drive pinmeans extending from said plate means into said hub, said hub havingopening means for receiving said drive pin means with clearancetherebetween that forms an oil passage leading from said fluid chamber,and fluid passage means in said pin means communicating with said clutchcontrol chamber which cooperates with said opening means to seal saidchambers from hydraulic communication in a first condition of operationof said unit and to hydraulically connect said chambers in a secondcondition of operation of said unit.

5. In a hydrodynamic unit having a housing, a rotatable drive plateoperatively connected to said housing to form a torus chamber therewith,input and output rotor means disposed in said torus chamber, said inputrotor means operatively connected to said housing for rotationtherewith, clutch means selectively engageable with said drive plate toselectively drivingly connect said input and output rotor means, saidclutch means being operatively disposed in said torus chamber and havinga clutch plate cooperating with said drive plate to form a clutchchamber separate from said torus chamber, said output rotor means havinga hub portion with an opening formed therein, drive means supported bysaid clutch plate which extends into said opening in said hub portionfor driving said output rotor means when said clutch means is drivinglyengaged, and fluid passage means in said drive means for providing forhydraulic communication between said torus chamber and said clutchchamber to cause the drive disengagement of said clutch means in a firstposition of said drive means relative to said opening and to seal saidchambers in a second position of said drive member relative to saidopening so that said clutch means can be drivingly engaged with saiddrive plate subsequent to the rotation of said input rotor faster thansaid output rotor means.

1. A power transmitting hydrodynamic unit comprising a housing defining a fluid chamber, input rotor means operatively connected to said housing for circulating transmission oil in said unit, output rotor means for receiving oil circulated by said input rotor means and for directing said oil back toward said input rotor means, torque transmitting means operatively connected to said output rotor means for transmitting the torque developed thereon by the circulating oil within said unit, clutch means in said unit selectively engageable to operatively connect said input rotor means with said torque transmitting means, said clutch means forming a clutch control chamber in said unit, drive means operatively connecting said clutch means to said output rotor means, and valve means operatively connected between said clutch means and said output rotor means to establish hydraulic communication between said fluid chamber and said clutch chamber in response to the overrun of said input rotor means by said output rotor means to reduce the load carrying capacity of said clutch and also to seal said chambers from hydraulic communication in Response to the overrun of said output rotor means by said input rotor means so that the load carrying capacity of said clutch can be increased.
 2. In a hydrodynamic unit comprising a rotatable drive plate and a housing secured thereto to form a torus chamber, input rotor means operatively connected to said housing for rotation therewith to drive transmission oil supplied to said chamber, output rotor means for receiving oil circulated by said input rotor means and for directing circulated oil back toward said input rotor means, selectively engageable clutch means operatively disposed in said torus chamber for mechanically connecting and for disconnecting said input rotor means and said output rotor means, said clutch means having a clutch plate disposed adjacent to said drive plate to form a clutch control chamber, said output rotor means having a hub portion with an enlarged cylindrical opening therein, a drive means supported by said clutch plate which extends into said opening to form a fluid passage therewith, and fluid passage means in said drive means having an opening cooperating with said hub to hydraulically seal said clutch chamber from said torus chamber when said input rotor means rotates faster than said output rotor means so that the oil pressure in said torus chamber can urge said clutch into engagement and further cooperating with said hub to open said clutch chamber to the torus chamber when said output rotor means rotates faster than said input rotor means to provide for the hydraulic communication of said chambers to cause the drive disengagement of said clutch means and the disconnection of the mechanical drive between said input and output rotor means.
 3. A power transmitting hydrodynamic unit comprising a rotatable housing defining a fluid chamber for receiving transmission oil, bladed input rotor means operatively connected to said housing for circulating transmission oil within said unit, bladed output rotor means for receiving oil circulated by said input rotor means and for discharging transmission oil in a circuitous path back toward said input rotor means, torque transmitting means for transmitting torque developed by said output rotor means from the oil circulated thereto by said input rotor means, connector means for drivingly securing said output rotor means to said torque transmitting means, clutch means for mechanically connecting and for disconnecting said input rotor means and said output rotor means, said clutch means comprising clutch plate means operatively disposed within said housing and cooperating directly therewith to define a clutch control chamber separate from said fluid chamber, valve means operatively disposed between said plate means and said output rotor means and responsive to the back drive of said output rotor means by said torque transmitting means to hydraulically connect said clutch control chamber and said fluid chamber so that said clutch means disconnects said input rotor means and output rotor means and being further responsive to the drive of said torque transmitting means by said output rotor means to hydraulically block communication between said clutch control chamber and said fluid chamber so that said clutch means can be engaged to drivingly connect said input rotor means and said output rotor means.
 4. The power transmitting unit of claim 3, said unit having a bladed stator therein operatively disposed between said input and output rotor means, a one-way brake for holding said stator from rotating in a first direction and permitting the rotation thereof in an opposite direction, said output rotor means having a hub fastened by said connector means to said torque transmitting means, said valve means comprising drive pin means extending from said plate means into said hub, said hub having opening means for receiving said drive pin means with clearance therebetween that forms an oil passage leading from said fluid chamber, and fluid passage means in said pin means communicating with said clutch controL chamber which cooperates with said opening means to seal said chambers from hydraulic communication in a first condition of operation of said unit and to hydraulically connect said chambers in a second condition of operation of said unit.
 5. In a hydrodynamic unit having a housing, a rotatable drive plate operatively connected to said housing to form a torus chamber therewith, input and output rotor means disposed in said torus chamber, said input rotor means operatively connected to said housing for rotation therewith, clutch means selectively engageable with said drive plate to selectively drivingly connect said input and output rotor means, said clutch means being operatively disposed in said torus chamber and having a clutch plate cooperating with said drive plate to form a clutch chamber separate from said torus chamber, said output rotor means having a hub portion with an opening formed therein, drive means supported by said clutch plate which extends into said opening in said hub portion for driving said output rotor means when said clutch means is drivingly engaged, and fluid passage means in said drive means for providing for hydraulic communication between said torus chamber and said clutch chamber to cause the drive disengagement of said clutch means in a first position of said drive means relative to said opening and to seal said chambers in a second position of said drive member relative to said opening so that said clutch means can be drivingly engaged with said drive plate subsequent to the rotation of said input rotor faster than said output rotor means. 